Friday, June 2, 2017

Maudlin accepts the reality of time

People often say, “I’m forced into believing in a block universe because of relativity.” The block universe, again, is some kind of rigid structure. The totality of concrete physical reality is specifying that four-dimensional structure and what happens everywhere in it. In Newtonian mechanics, this object is foliated by these planes of absolute simultaneity. And in relativity you don’t have that; you have this light-cone structure instead. So it has a different geometrical character. But I don’t see how that different geometrical character gets rid of time or gets rid of temporality.

The idea that the block universe is static drives me crazy. What is it to say that something is static? It’s to say that as time goes on, it doesn’t change. But it’s not that the block universe is in time; time is in it. When you say it’s static, it somehow suggests that there is no change, nothing really changes, change is an illusion. It blows your mind. Physics has discovered some really strange things about the world, but it has not discovered that change is an illusion.

For instance, Brad Skow adopts the “block universe” concept arising from Special Relativity and concludes that time doesn’t “pass” in the sense of flowing; rather, “time is part of the uniform larger fabric of the universe, not something moving around inside it.”

Relativity convinced most physicists that we live in a “block universe” in which past, present, and future are equally real. In that case, there’s no reason to suppose the past influences the future, but not vice-versa. Although their theories shout retrocausality, physicists haven’t fully grappled with the implications yet.

This is nonsense, of course. Relativity is all about how the past influences the future. A central premise is that all causality is within light cones.

It would be easier to deny the reality of time with pre-relativity physics. That allowed action-at-a-distance, and violated intuitions about causality. One could believe that planetary orbits were determined independently of time.